update: Major Overhault to all subsystems

backend/Dockerfile

@@ -1,5 +1,15 @@
 FROM python:3.11-slim
 
+# WeasyPrint system dependencies (libpango, libcairo, etc.)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpango-1.0-0 \
+    libpangocairo-1.0-0 \
+    libgdk-pixbuf-2.0-0 \
+    libffi-dev \
+    shared-mime-info \
+    fonts-dejavu-core \
+    && apt-get clean && rm -rf /var/lib/apt/lists/*
+
 WORKDIR /app
 
 COPY requirements.txt .